Getting error SyntaxError: (ruby filter code):3: syntax error, unexpected kIN logstash

As per my understanding if I use below option it will split the strings in same field 'Label'.
mutate {
split => { "label" => "-" }
}

Currently I have three columns:
Header: Label|ResponseCode|URL
Value: Thread-group1-transaction_1|200|Null
Value: Thread-group1-transaction_1-Request1|200|http://google.co.in
Value: Thread-group1-transaction_1-Request2|200|http://google.co.in/image
Value: Thread-group1-transaction_1-Request3|300|http://google.co.in
and so...
However my requirement is to store "Thread-group1-transaction_1-Request" in such a way that when I search for Request; get corresponding column value of URL, when search for transaction get their corresponding value i.e.Null.

I believe storing each segment in separate field will help in searching. Is it posssible to split and store in separate fields.